Every electronic circuit is designed to operate off of some supply voltage, which is usually assumed to be constant. A voltage regulator provides the constant DC output voltage and contains circuitry that continuously holds the output voltage at a regulated value regardless of changes in a load current or input voltage. A linear voltage regular operates by using a voltage current source to output a fixed voltage. A control circuit must monitor the output voltage and adjust the current source to hold the output voltage at the desired value.
Circuit designers have limited options for the drive voltages applied to the drive circuits of transistor switches for switched power supplies. They can use the input voltage Vin which for many applications will be equal to 12 volts or the system bias voltage VCC which normally comprises 5 volts. If the higher voltage Vin is used as the gate driver voltage, there are efficiency losses at the low end of the load current for the switched power supply circuit. If the system voltage VCC is used as the drive voltage, the high end efficiencies are lost for higher load currents. Thus, there is a need for a gate driver topology that provides maximum load efficiency over a wide variety of load current ranges of switched power supplies.